How Common Are Severe Thunderstorms In Alaska?

We deal with some pretty rough weather here in the lower 48. It’s hard to find a day during the warm season when some town somewhere doesn’t get trashed by the fits of a raging thunderstorm. The heart of severe weather beats in the central and southern United States, creating a bullseye that exists there from Valentine’s Day through Halloween. The frequency of bad storms drops—but doesn’t disappear—the farther north you go in the United States.

But what about Alaska?

It’s easy to forget about Alaska even though it’s by far the largest of the 50 states. Separated from us by an entire country and broken off, shrunk, and shoved into the bottom-left corner of most maps, Alaska is undeservedly an afterthought for many Americans. When you do think of Alaska, your first thought likely conjures up images endless cold and snow interrupted by a small window of comfortable weather.

Despite its reputation, parts of Alaska can get pretty toasty during the summer. Much of the state recently endured a stretch of temperatures you’d more commonly see in Minnesota than in Alaska. Fairbanks, a city that’s geographically planted just right of center in the state’s otherwise unpopulated wilderness, recorded two high temperatures of 88°F earlier this month. The city has recorded highs of 80°F or warmer 10 times since June 1; average highs in Fairbanks range from the upper 60s in June to the mid-70s in July. This month also saw the all-time record warmest temperature ever recorded so close to the Arctic Ocean when a small town in far northern Alaska reached a daytime high of 84°F.

Alaska went through an extended period of abnormally warm weather; such summertime temperatures aren’t common but they’re not unheard of either. The all-time record high temperature in Fairbanks was 96°F set on June 16, 1969, and the main airport there has seen temperatures at or above 90°F on 35 different days since records began in December 1929. Fairbanks is a hot spot given its location, but it can get relatively warm in the southern part of the state as well, climbing up into the 80s on the balmiest days.

Lightning strikes recorded in Alaska and western Canada between June 29, 2016, and July 13, 2016. | Image: BLM

Since warm, unstable air is the fuel that feeds a thunderstorm, talking about the warmth in Alaska helps us understand how common severe thunderstorms are there. The state is no stranger to thunderstorms. During the heat wave earlier this month, lightning monitors detected tens of thousands of lightning strikes across the state during the two-week period between June 29 and July 13.

A severe thunderstorm in the United States is one that produces damaging hail the size of a quarter or larger, wind gusts of 60 MPH or stronger, or a tornado. It takes the right combination of environmental factors like instability and wind shear for thunderstorms to grow strong enough that they can suspend large chunks of hail in the air or generate winds strong enough to cause damage, so thankfully only a fraction of thunderstorms around the world reach severe levels.

This is the case in Alaska, where only a small number of thunderstorms are able to grow strong enough that they produce quarter-size hail or 60+ MPH wind gusts.

Severe thunderstorm warnings issued in the State of Alaska between 2002 and 2016. | Map: Dennis Mersereau, Data: IEM/NWS

Data pulled from the Iowa Environmental Mesonet—a treasure trove of weather data—shows that the National Weather Service offices in Anchorage and Fairbanks have collectively issued 55 severe thunderstorm warnings since 2002, four of those warnings going up within the last two months. To put that in perspective, the NWS office that serves the area around Boston, Massachusetts, has issued 78 severe thunderstorm warnings between January 1 and July 28 of this year.

Most of the warnings are concentrated around Anchorage, Fairbanks, and Bethel. Radar coverage in The Last Frontier is about as sparse as its population, so if a storm doesn’t form near one of the cities covered by this lifesaving technology, forecasters only have eyes on the ground and satellite imagery to keep track of it.

Alaska averages a couple of severe thunderstorm warnings every year, though it’s hard to verify if the warned storms actually produced severe weather (and if any unwarned storms produced severe weather) due to the state’s sparsely-populated nature. If a tree falls in the forest and nobody is around to see it, the damage goes unreported to the National Weather Service and we’ll never know for sure if the storm was indeed severe. We have the same problem in some parts of the lower 48, though to a lesser extent.

Tornadoes are even less common in Alaska, with the three National Weather Service offices in the state holding the distinction of being the only offices out of the 100+ in the 50 states that have never before issued a tornado warning. The residents of Alaska have reported a whopping four tornadoes since reliable records began in 1950, none of which produced notable damage. The most recent tornado report from Alaska came from Sand Point, a small town on an island near the beginning of the Aleutian Island chain. Residents reportedly watched the tornado from afar as it moved across nearby mountains.